The present invention relates to a plasma processing apparatus and a plasma processing method for detecting an end point of etching in etching processing of a substrate-like sample upon manufacturing of a semiconductor integrated circuit. In particular, the present invention relates to a plasma processing apparatus and a plasma processing method which execute the etching processing of a film structure containing a film to be processed, provided preliminarily on the upper or top surface of the substrate-like sample such as a semiconductor wafer mounted in a processing chamber inside a vacuum vessel, using plasma formed in the processing chamber while detecting a current processed condition.
In a step of manufacturing a semiconductor device from the substrate-like sample such as a semiconductor wafer, dry-etching technology has been widely used in which plasma formed in the processing chamber inside the vacuum vessel has been employed to form film layers of various materials on the surface of the wafer, particularly, for removal of film layers of dielectric material or formation of a pattern on the film. In such an etching processing apparatus using plasma, generally, processing gas introduced into the processing chamber which serves as a processing space within the vacuum vessel is reacted with electric field or magnetic field to produce plasma. Then, the film structure containing a film layer to be processed arranged preliminarily on the surface of a wafer is reacted with charged particles such as ions in the obtained plasma or high-active particles (radical) to etch the film to be processed.
In the wafer etching processing, it has been known that the intensity of light emitted by the formed plasma at a particular wavelength changes with a progress of etching of the film being processed. Then, according to a conventionally-known technology, a change in the intensity of emitted light at a particular wavelength from the plasma is detected during the processing, and an etching end point in which a film has been removed by etching or a predetermined depth has been reached by etching is detected based on a detection result.
Particularly, to achieve a higher integration of a semiconductor device and a higher miniaturization of its processing, it has been important to finish the processing in the etching process with the residual thickness of the film to be processed secured in a predetermined value. As a technology for finishing the etching processing with the thickness of the film to be processed in a predetermined value, there has been known a technology for detecting a residual film thickness using a change in the intensity of interference light, based on a knowledge that as the residual thickness of the film to be processed decreases with a progress of the etching processing, light emitted from the wafer surface containing the film to be processed forms an interference waveform.
For example, JP-A-2001-085788 (corresponding to U.S. Pat. No. 6,541,388) has disclosed a technology in which at least two kinds of wavelengths of the interference light are detected and then, the residual thickness of the film to be processed is detected by using the intensity of the interference light of those plural wavelengths.
In addition, JP-A-2003-083720 has disclosed a technology in which the interference light of plural wavelengths is detected and then, a pattern regarding the intensity of the interference light using each of preliminarily obtained plural wavelengths as a parameter is compared with data regarding the intensity of actually obtained interference light to detect the residual thickness of the film to be processed.